JP2020504113A - Parallel reactor system for ethylbenzene dehydrogenation - Google Patents

Abstract

In a first stage, a feed stream containing hydrocarbons and steam is contacted with a dehydrogenation catalyst under dehydrogenation conditions to obtain a first stage effluent, heating the first stage effluent, and Contacting the heated first stage effluent with a dehydrogenation catalyst under dehydrogenation conditions in a two stage to obtain a second stage effluent containing the dehydrogenation product, wherein the first stage effluent comprises The step includes a first reaction vessel and a second reaction vessel arranged in parallel, and wherein the second step includes a third reaction vessel connected in series with the first reaction vessel and the second reaction vessel. , Multi-stage dehydrogenation method. A multi-stage dehydrogenation system for performing dehydrogenation is also provided. [Selection diagram] Fig. 1

Description

  The disclosed systems and methods relate to dehydrogenation reactions, such as the dehydrogenation of ethylbenzene to styrene monomers. More specifically, the disclosed systems and methods relate to multi-stage dehydrogenation. More specifically, the disclosed system and method comprises a first stage comprising two dehydrogenation reactors arranged in parallel, and a third dehydrogenation reactor present in series with said dehydrogenation reactor. And a second stage.

Relation with Related Application This application is related to 35U. S. C. §119 (e), claiming priority of US Provisional Patent Application No. 62 / 436,653, filed December 20, 2016, entitled "Parallel Reactor System for Ethylbenzene Dehydrogenation," The disclosures are all incorporated herein by reference.

Federally funded research and development statement Not applicable

Refer to microfish technical data Not applicable

  Styrene, a major polymer-forming raw material such as polystyrene, acrylonitrile, butadiene styrene, styrene-butadiene rubber, and others, is consumed in enormous amounts annually and is one of the typical commodity monomer products. Conventional styrene production plants use a reaction system that includes two or three adiabatic reactors connected in series with multiple furnaces and heat exchangers. Styrene can be prepared by dehydrogenating ethylbenzene in the presence of superheated steam, ie, steam, on a dehydrogenation catalyst bed in a reactor. In view of the commercial importance of styrene production, there is a continuing need for improved systems and methods for performing dehydrogenation reactions, such as the dehydrogenation of ethylbenzene, to produce styrene. Desirably, such improved systems and methods reduce the reaction pressure, increase the selectivity, and provide the required conversion and / or 1 pound of the desired dehydrogenation product per desired product, as described in detail below. It may be possible to lower the energy input.

Disclosed herein is a multi-stage dehydrogenation process wherein, in a first stage, a feed stream containing hydrocarbons and steam is contacted with a dehydrogenation catalyst under dehydrogenation conditions. Obtaining a first stage effluent, heating the first stage effluent, and, in a second stage, contacting the heated first stage effluent with a dehydrogenation catalyst under dehydrogenation conditions; Obtaining a second stage effluent containing the dehydrogenation product, wherein the first stage includes a first reactor and a second reactor arranged in parallel, wherein the second stage comprises: A third reaction tank is connected in series with the first reaction tank and the second reaction tank. In an embodiment, contacting the feed stream in the first stage comprises contacting a first portion of the feed stream with a dehydrogenation catalyst in a first reactor to obtain a first reactor effluent, and Contacting a second portion of the stream with the dehydrogenation catalyst in a second reactor to obtain a second reactor effluent. In embodiments, the method further comprises combining the effluent of the first reactor and the effluent of the second reactor to form a first stage effluent prior to the heating step. In an embodiment, the method further comprises heat exchanging the feed stream with the second stage effluent, thereby condensing a portion of the second stage effluent; and compressing the second stage effluent after the heat exchange step. And separating the dehydrogenated product from the effluent of the second stage. In an embodiment, the total differential pressure (t
The total differential pressure is lower than the total differential pressure in a similar manner except that the first, second and third reactors are connected in series, where the total differential pressure is at the inlet of the first reactor. And the third reactor outlet. In embodiments, the overall selectivity of the multi-stage dehydrogenation process is less than that of a similar process except that the first, second and third reactors are connected in series. Is large, where the total selectivity is
[Mole of desired product (for example, dehydrogenated product) produced in first, second and third reactors] / [in first, second and third reactors] Total moles of converted dehydrogenated feed species (eg, hydrocarbons)
Is defined as In an embodiment, the total energy input of the multi-stage dehydrogenation process is the total energy input of a similar process except that the first, second, and third reactors are connected in series. Lower than. In embodiments, the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene. In an embodiment, each of the first, second and third reactors is an adiabatic reactor. In embodiments, a heat exchanger is used to heat the first stage effluent.

Also disclosed herein is a multi-stage dehydrogenation system comprising: a feed stream comprising hydrocarbons and steam; a first stage having first and second reactors arranged in parallel. Wherein the first reactor comprises a dehydrogenation catalyst and has a first reactor inlet for receiving a portion of the feed stream, wherein the second reactor comprises a dehydrogenation catalyst. Having a second reactor inlet containing and receiving the remainder of the feed stream, wherein the first stage comprises dehydrating the hydrocarbon with the dehydrogenation catalyst in the first and second reactors. The first stage, which is effective to convert at least a portion of the hydrocarbons to dehydrogenation products by contacting under the conditions of the hydrogenation, is fluidized into the first reactor outlet of the first reactor. Connected and receives the effluent of the first reactor and flows to the second reactor outlet of the second reactor A second stage having an inter-stage heater for receiving the effluent of the second reactor and a third reactor, wherein the third reactor is dehydrogenated A third reaction vessel inlet that includes a reaction catalyst and that is connected to the heater by a flow path, and wherein the second stage includes distributing unreacted hydrocarbons received from the interstage heater in the third reaction vessel. Contacting the dehydrogenation catalyst with the unreacted hydrocarbon under dehydrogenation conditions to convert to dehydrogenation products to provide a second stage effluent including the effluent from the third reactor A second stage that is effective. In an embodiment, the effluent of the first reactor and the effluent of the second reactor are combined to form a first stage effluent, which is supplied to the interstage heater. In embodiments, the interstage heater is a heat exchanger that uses steam as the fluid to be heated. In an embodiment, the system further comprises a first heat exchanger for exchanging a first heat between the second stage effluent and the feed stream; and a second heat between the second stage effluent and the feed stream. A second heat exchanger to be replaced is included. In an embodiment, the system further comprises a compressor configured to compress the second stage effluent and downstream of the first and second heat exchangers, a downstream of the compressor, and a dehydrogenation product. From the second stage effluent. In an embodiment, the total differential pressure of the multi-stage dehydrogenation process is lower than the total differential pressure of a similar system except that the first, second and third reactors are connected in series, where The total differential pressure is measured between the first reactor inlet and the third reactor outlet. In an embodiment, the overall selectivity of the multi-stage dehydrogenation process is greater than the overall selectivity of a similar system except that the first, second and third reactors are connected in series. And the total selectivity is:
[Mole of desired product (eg, dehydrogenated product) generated in first, second and third reaction vessels] / [in first, second and third reaction vessels] Total moles of converted dehydrogenated feed species (eg, hydrocarbons)
Is defined as In an embodiment, the total energy input of the multi-stage dehydrogenation process is lower than the total energy input of a similar system except that the first, second, and third reactors are connected in series. In embodiments, the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene. In an embodiment, each of the first, second and third reactors is an adiabatic reactor.

  Also disclosed herein is a multi-stage dehydrogenation process in which steam and ethylbenzene are combined to form a feed stream; heating the feed stream to obtain a heated feed stream; Dividing the first part of the feed stream into a first reactor containing a dehydrogenation catalyst where ethylbenzene is converted to styrene; the second part of the feed stream is dehydrogenated Feed to a second reactor containing the conversion catalyst, where ethylbenzene is converted to styrene; recovering a first effluent containing unreacted ethylbenzene and styrene from the first reactor; unreacted from the second reactor Recovering a second effluent containing ethylbenzene and styrene; combining the first effluent and the second effluent with the mixed effluent; heating the mixed effluent to obtain a heated mixed effluent; , A third reaction containing a dehydrogenation catalyst Feeding to the vessel, where at least a portion of the unreacted ethylbenzene present in the heated mixed effluent is converted to styrene; and recovering a third effluent containing unreacted ethylbenzene and styrene from the third reactor. It is a multi-stage dehydrogenation method.

  The detailed description refers to the drawings, briefly described below, wherein like reference numerals represent like parts.

1 is a process flow diagram of a multi-stage dehydrogenation system according to an embodiment of the present disclosure. FIG. 4 is a process flow diagram of a multi-stage dehydrogenation system according to another embodiment of the present disclosure. 1 is a process flow diagram of a conventional multi-stage dehydrogenation system.

  Conventional methods for dehydrogenation (eg, dehydrogenation of ethylbenzene) generally involve steam dilution, low pressure operation, and adiabatic reaction vessels. In the endothermic reaction, a reheater is arranged between the adiabatic reaction tanks. Since low pressures may be preferred for the dehydrogenation reaction, the reactor is generally operated at low pressure by introducing a compressor (eg, a vacuum compressor) into the eluate line (ie, reduced pressure conditions). Conventional three-bed reactor systems are arranged in series and retrofits are usually selected to increase plant capacity. For example, the dehydrogenation of ethylbenzene is an endothermic reaction, and involves a series of adiabatic reactors that include steam dilution and a reheater located between the reactors.

  As described above, normal dehydrogenation uses three dehydrogenation reactors arranged in series. Surprisingly, for a multi-stage dehydrogenation application, placing the first two reactors side by side and subsequently feeding their product streams together into a common third reactor requires the entire reaction. It has been found that it may be possible to reduce the pressure in the vessel, reduce the energy required and / or increase the selectivity of the product, while maintaining the desired conversion. However, the systems and methods disclosed herein may make the systems and methods disclosed herein suitable for various dehydrogenation reactions, as described below in connection with the dehydrogenation of ethylbenzene to produce styrene monomers. It will be obvious.

Implementations of the specific descriptions of one or more aspects are specifically described below, and the disclosed assemblies, systems, and methods are not limited to any number, whether now known or not yet present. It should be understood first that the technique can be implemented using the techniques described above. This disclosure should not be limited in any way to the specifically described implementations, drawings and techniques described below,
It may be modified within the scope of the appended claims and their completely equivalent scope. Although values relating to dimensions of various elements are disclosed, the drawings are not to scale.

  Disclosed herein are systems and methods for multi-stage dehydrogenation. This system and method uses three reactors, as will be described in more detail below, of which the first two are arranged in parallel and feed continuously to a common third reactor. As mentioned above, such a parallel arrangement of the first two reactors may allow to reduce the overall reactor pressure, reduce energy requirements and / or increase selectivity.

  Disclosed herein is a system for multi-stage dehydrogenation. The system includes a first stage including a first dehydrogenation reactor and a second dehydrogenation reactor arranged in parallel, a third stage disposed in series with the first stage, and includes a third dehydrogenation reactor. A second stage, fluidly connected to each of the first and second dehydrogenation reactor outlets and increasing the temperature of the reactor effluent therefrom, and increasing the temperature of the reactor effluent An interstage heater configured to introduce the liquid into the third dehydrogenation reactor. The system further comprises one or more heaters in addition to the interstage heaters, one or more heat exchangers, one or more flow splitters or mixers, and various downstream processing equipment, such as a third reactor May comprise a compressor and separator configured to separate the multi-stage dehydrogenation product from the reactor effluent extracted from the reactor. For example, in an embodiment as described below in connection with FIG. 1, a multi-stage dehydrogenation system according to the present disclosure is configured to exchange a first heat between a second stage effluent and a feed stream. And may further include a second heat exchanger configured to exchange a second heat between the second stage effluent and the feed stream. In some embodiments, the multi-stage system of the present disclosure is further located downstream of the third reactor, the first heat exchanger, and / or the second heat exchanger, and compresses the second stage effluent. And may also include, in embodiments, a separation system located downstream of the compressor and configured to separate the dehydrogenated product from the second stage effluent. Each component of the system of the present disclosure referred to above will now be described in further detail with reference to the embodiment of FIG.

  FIG. 1 is a process flow diagram of a multi-stage dehydrogenation system I according to an embodiment of the present disclosure. The multi-stage dehydrogenation system 1 includes first and second reaction stages in series, each stage comprising at least a portion of the hydrocarbons in the feed stream, including hydrocarbons and steam, wherein the hydrocarbons are dehydrogenated with It is effective to convert to a dehydrogenation product by contacting under dehydrogenation conditions. The first reactor stage of the multi-stage dehydrogenation system I comprises a first dehydrogenation reactor 65A and a second dehydrogenation reactor 65B arranged in parallel, and The second reactor stage includes a third dehydrogenation reactor 65C. The multi-stage dehydrogenation system I further includes a first heater 15A, a second heater 15B, a third heater 15C, a fourth heater 15D, and an inter-stage heater 15E (here, "fifth heater 15E ), A flow splitter 55A, a mixer 55B, a first heat exchanger 25A and a second heat exchanger 25B. Each component of the multi-stage dehydrogenation system I is described in further detail below.

The first heater 15A includes a hydrocarbon feed introduced into the first heater via the hydrocarbon feed inlet line 10, and a vaporizer introduced into the first heater via the vaporized steam feed inlet line 5. Combined with the steam, it is configured to generate a first heater effluent in the first heater effluent line 20. The first heater 15A can be operated to vaporize the hydrocarbon feed introduced therein, and is therefore sometimes referred to herein as "vaporizer vapor mixing unit 15A". The first heater 15A is fluidly connected to the first heat exchanger 25A via the first heater effluent line 20. The first heat exchanger 25A exchanges heat between the first heater effluent in the first heater effluent line 20 and the second heater effluent in the second heater effluent line 95. It is configured as follows. Since the first heat exchanger 25A is operable to vaporize hydrocarbons introduced therein via the first heater effluent line 20, the first heat exchanger 25A is referred to herein as "reactor feed". The first heat exchanger effluent line 30 is configured to withdraw effluent containing the reactor effluent from the first heat exchanger 25A when referred to as "vaporizer 25A". It is configured for retrieval.

  The first heat exchanger 25A is fluidly connected to the second heat exchanger 25B via the first heat exchanger effluent line 30, and feeds the reactor feed in the first heat exchanger effluent line 30. It is configured to exchange heat between the containing first heat exchanger effluent and the third reactor effluent extracted from the third dehydrogenation reactor 65C via the third reactor effluent line 85. ing. The second heat exchanger effluent line 90 is configured to withdraw effluent containing dehydrogenation products from the second heat exchanger 25B, and the second heat exchanger effluent line 35 is It is configured to take out the effluent containing the reaction vessel feed from the heat exchanger 25B. The second heat exchanger 25B includes a third dehydrogenation effluent extracted from the third dehydrogenation reaction tank 65C via the third reaction vessel effluent line 85, and a first heat exchanger effluent line 30. The second heat exchanger 25B is also referred to herein as "reactor feed / effluent exchange" because it is configured to transfer heat from the first heat exchanger effluent containing the reactor feed therein. 25B ". The second heater 15B receives and heats the second heat exchanger effluent containing the dehydrogenation product introduced therein via the second heat exchanger effluent line 90, and heats the second heater effluent. It may be arranged to provide a second heater effluent extracted therefrom via the liquid line 95. Because the second heater 15B can be operated to produce high pressure (HP) steam, the second heater 15B may be referred to herein as an "HP steam generator 15B."

  The third heater 15C is configured to generate a third heater effluent from the dilution steam introduced via the dilution steam supply line 40. The third heater 15C is referred to herein as a "first steam superheater 15C" because the third heater 15C is operable to superheat the dilution steam introduced therein via the dilution steam supply line 40. There are cases. The third heater 15C is fluidly connected to the fourth heater 15D via the third heater effluent line 45. The fourth heater 15D separates the dilution steam introduced therein via the third heater effluent line 45 and the hydrocarbon feed introduced therein via the second heat exchanger effluent line 35. It is configured to generate a fourth heater effluent. The fourth heater 15D provides dilute vapor mixing (ie, the contents of lines 35 and 45 are combined and discharged via effluent line 50), so that fourth heater 15D is referred to herein as " It may be referred to as “dilution vapor mixing unit 15D”. A fourth heater effluent line 50 (also referred to herein as a "first stage feed line 50") is fluidly connected to the fourth heater 15D and the flow splitter 55A, and from the fourth heater 15D. It is configured for the extraction of first stage reactor feeds and their introduction into flow splitter 55A.

  Flow splitter 55A is configured to split the first stage reactor feed introduced into 55A via fourth heater effluent line 50 for introduction into parallel dehydrogenation reactors 65A and 65B. ing. The flow splitter 55A is connected to the first dehydrogenation reaction tank 65A via the first dehydrogenation reaction tank supply line 60A and to the second dehydrogenation reaction tank 65B via the second dehydrogenation reaction tank supply line 60B. Fluidly connected to

  First dehydrogenation reactor 65A contains a dehydrogenation catalyst and, via first dehydrogenation reactor feed line 60A, a first stage feed comprising hydrocarbons and steam in first stage feed line 50 The second dehydrogenation reactor 65B also includes a dehydrogenation catalyst, and includes a first stage feed line 50B via a second dehydrogenation reactor feed line 60B. A second reactor inlet for receiving the remainder of the first stage feed, including hydrocarbons and vapors therein.

The first dehydrogenation reactor 65A is fluidly connected to the mixer 55B via the first reactor outlet; the second dehydrogenation reactor 65B is fluidly connected to the mixer 55B via the second reactor outlet. Have been. The mixer 55B includes a first dehydrogenation reaction tank effluent extracted from the first dehydrogenation reaction tank 65A via the first reaction tank effluent line 70A and a second reaction tank effluent line 70B via the second reaction tank effluent line 70B. The second dehydrogenation reactor effluent extracted from the second dehydrogenation reactor 65B is configured to combine to provide a combined first stage reactor effluent. The mixer 55B fluidly flows through a first mixing stage effluent line 75 to a fifth heater 15E (also referred to herein as an "interstage heater 15E" or a "third reactor reheater 15E"). It is connected. The fifth heater 15E controls the temperature of the first stage effluent introduced into 15E via the first stage effluent line 75 before being introduced into the second stage including the third dehydrogenation reaction tank 65C. It is configured to raise. A third reactor supply line 80 (also referred to herein as a "second stage supply line 80") fluidly connects the fifth heater 15E to the third dehydrogenation reactor 65C.

  As described above, the third reactor effluent line 85 containing the dehydrogenation product fluidly connects the third dehydrogenation reactor 65C to the second heat exchanger 25B. Also, as described above (and not shown in FIG. 1), the multi-stage dehydrogenation system I further includes downstream processing equipment known to those skilled in the art. As a non-limiting example, the multi-stage dehydrogenation system according to the present disclosure further comprises a compressor configured to introduce a third reactor effluent (eg, via the first heat exchanger effluent line 96); And a separation unit designed to separate dehydrogenated products from water and various by-products of the reaction.

  A multi-stage dehydrogenation system II according to another embodiment of the present disclosure is illustrated in the flow diagram of FIG. In this embodiment, a dilution steam supply line 40 'is configured to introduce a dilution steam feed into a third heater 15C' (also referred to herein as a "first steam superheater 15C '"). In this embodiment, it is fluidly connected to a third heat exchanger 25C 'via a third heater effluent line 45'. Line 41 'may fluidly connect third heat exchanger 25C' to dilution steam mixing unit 15D via third heater 15C and third heater effluent line 45. The third heater 15C provides additional reheating before mixing with the hydrocarbon vapor to enter the first set of reactors. In this embodiment, the interstage heater includes a heat exchanger 25C '. This embodiment, due to enhanced heat recovery and slightly lower total energy input, provides additional energy advantage over the embodiment of FIG. 1 as compared to the conventional embodiment of FIG. 3 described further herein below. It may allow for benefits.

  Dehydrogenation reactors 65A, 65B and 65C can be any dehydrogenation reactor known to those skilled in the art. In an embodiment, the dehydrogenation reactors 65A, 65B and 65C are adiabatic reactors. Dehydrogenation reactors 65A, 65B and 65C include therein a dehydrogenation catalyst suitable for catalyzing the dehydrogenation of hydrocarbons in the hydrocarbon feed to dehydrogenation products. In embodiments, the dehydrogenation catalyst is a catalyst operable to dehydrogenate ethylbenzene in a hydrocarbon feed to produce a dehydrogenation product comprising styrene. The choice of an appropriate dehydrogenation catalyst will be apparent to those skilled in the art based on the given reactor conditions. In embodiments, the dehydrogenation catalyst comprises potassium oxide or potassium carbonate, rare earth oxides, and / or iron (III) oxides promoted by other inorganic performance promoters. In embodiments, the dehydrogenation catalyst comprises a heterogeneous catalyst system suitable for operating at steam dilution, reduced pressure and elevated temperature to overcome equilibrium constraints and endothermic reactions.

Heaters 15A, 15B, 15C, 15C ', 15D and 15E can be any heater known to those skilled in the art. In embodiments, the one or more heaters 15A, 15B, 15C, 15C ', 15D and 15E are selected from a flame tube heater or a furnace. In embodiments, the one or more heaters 15A, 15B, 15C, 15C ', 15D and 15E are selected from heat exchangers. In embodiments, one or more heaters 15A, 15B, 15C
, 15C ', 15D and 15E are selected from heat exchangers that use steam as the heating fluid. In embodiments, the third heater 15C, the third heater 15C ', or both are steam superheaters. In an embodiment, interstage heater 15E includes a standard furnace reheater. In embodiments, interstage heater 15E includes a heat exchanger.

  Heat exchangers 25A, 25B and 25C 'can be any heat exchanger known to those skilled in the art to be suitable for heat exchange between a process stream and a heat exchange fluid. In embodiments, the heat exchange fluid includes steam. In an embodiment, the heat exchange fluid is a separate process stream (eg, a third reactor effluent in a third reactor effluent line 85, a second heat exchanger effluent in a second heat exchanger effluent line 90, Or the second heater effluent line 95 in the second heater effluent line 95). In embodiments, the heat exchangers 25A, 25B and / or 25C 'are selected from a shell and tube heat exchanger.

  As a comparison, a conventional dehydrogenation system III according to the prior art is illustrated in FIG. 3 and is mentioned for comparison in the following examples. The reference numerals in FIG. 3 roughly correspond to those in FIGS. 1 and 2, except for the case described below (specifically with respect to the fifth heater 15E), the components in FIG. Component 105 at 3 corresponds to component 5 in FIGS.

  In the conventional dehydrogenation system III, a first dehydrogenation reaction tank 165A, a second dehydrogenation reaction tank 165B, and a third dehydrogenation reaction tank 165C are connected in series. In this arrangement, the fourth heater effluent in the fourth heater effluent line 150 is not introduced into the flow splitter, but rather all is introduced into the first dehydrogenation reactor 165A. The effluent of the first dehydrogenation reactor is passed through the first reactor effluent line 170A to the second dehydrogenation reactor 165B via the third heat exchanger 125C and the third heat exchanger effluent line 127. be introduced. The third heat exchanger 125C provides heat between the first reactor effluent in the first reactor effluent line 170A and the vapor of the fifth heater effluent in the fifth heater vapor effluent line 129. Is configured to be replaced. Since the third heat exchanger 125C serves to reheat the reactants prior to the second dehydrogenation reactor 165B, the third heat exchanger 125C is referred to herein as "reactor 1 / reactor 2 reheat." 125C ". The second dehydrogenation reaction tank effluent is introduced into the third dehydrogenation reaction tank 165C via the second reaction tank effluent line 170B via the fourth heat exchanger 125D and the third reaction tank supply line 180. Is done. Since fourth heat exchanger 125D may provide a heated feed to third dehydrogenation reactor 165C, fourth heat exchanger 125D may also be referred to herein as "reactor 2 / reactor 3". Reheater 125D ".

Dilution steam supply inlet line 140 'is configured to introduce dilution steam into third heater 15C', which is configured to heat the dilution steam. Since the third heater 115C 'may operate to superheat the dilution steam introduced therein, the third heater 115C' may also be referred to herein as "the first steam superheater 115C '." is there. The third heater effluent line 145 'fluidly connects the third heater 115C' to the fourth heat exchanger 125D, which removes heat from the steam in the third heater effluent line 145 '. Transfer to the second reactor effluent introduced into the fourth heat exchanger 125D via the second reactor effluent line 170B and thus the third dehydrogenation reactor via the third reactor supply line 180 The second reactor effluent is heated for introduction into 165C and provides cooled steam extracted from fourth heat exchanger 125D via fourth heat exchanger steam effluent line 128. A fourth heat exchanger vapor effluent line 128 fluidly connects the fourth heat exchanger 125D to a fifth heater 115E (which is not the interstage heater in this conventional case), which is introduced there. And configured to heat the cooled steam. Since fifth heater 114E can be operated to provide superheated steam, fifth heater 115E may be referred to herein as "second steam superheater 115E." The fifth heater effluent line 129 fluidly connects the fifth heater 115E to the third heat exchanger 125C, which is connected to the first reactor effluent line 170A in the first reactor effluent line 170A as described above. And heat in the fifth heater vapor effluent line 129 to exchange heat with the vapor in the fifth heater effluent line. The third heat exchanger vapor effluent line 126 fluidly connects the third heat exchanger 125C to the sixth heater 115F, which is introduced there via the third heat exchanger vapor effluent line 126. Configured to heat the cooled steam in a fourth heater 155D prior to combining with the second heat exchanger effluent containing the reactor feed in the second heat exchanger effluent line 135. I have. The sixth heater 115F may also be referred to herein as a "third steam superheater 115F" because the sixth heater 115F can be operated to superheat the steam introduced therein.

  Components 105 (vaporized vapor feed inlet line), 110 (hydrocarbon feed inlet line), 115A ("first heater" or "vaporized steam mixing unit"), 115B ("second heater") in FIG. Or "HP steam generator"), 120 (first heater effluent line), 125A ("first heat exchanger" or "reactor feed vaporizer"), 125B ("second heat exchanger" or "Reactor feed / effluent exchanger"), 130 (first heat exchanger effluent line containing reactor feed), 190 (second heat exchanger effluent line containing dehydrogenated product), 195 (The second heater effluent line containing the dehydrogenation reaction product) and 196 (the first heat exchanger effluent line containing the dehydrogenation product) correspond to components 5, 10, 15A, 15B of FIGS. , 20, 25A, 25B, 30, 90, 95 and It has been described with beauty 96 references.

  Also disclosed herein is a method for multi-stage dehydrogenation. The multi-stage process comprises, in a first stage, contacting a feed stream containing hydrocarbons and steam with a dehydrogenation catalyst under dehydrogenation conditions to obtain a first stage effluent; And, in a second stage, contacting the heated first stage effluent with a dehydrogenation catalyst under dehydrogenation conditions to obtain a second stage effluent containing the dehydrogenation product, Wherein the first stage comprises a first reactor and a second reactor arranged in parallel, and the second stage comprises a third reactor connected in series to the first reactor and the second reactor. Including. In embodiments, the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene. In an embodiment, each of the first, second and third reactors is operated adiabatically.

  A more detailed description of the multi-step method according to embodiments of the present disclosure will now be made with reference to FIG.

The vaporized steam feed in the vaporized steam feed inlet line 5 and the hydrocarbon feed in the hydrocarbon feed inlet line 10 are combined in a first heater 15A, where the hydrocarbons are vaporized and the hydrocarbons are vaporized. A first heater effluent containing feed is provided, which is extracted from the first heater 20 via the first heater effluent line 20. Through a passage through the first heat exchanger 25A and the second heat exchanger 25B, heat is transferred to the vaporized hydrocarbon feed and the third reactor effluent (ie, product stream) in the third reactor effluent line 85. ) And exchanged between. In the first heat exchanger 25A, heat is transferred to the second heater effluent including the vaporized hydrocarbon feed in the first heater effluent line 20 and the dehydrogenated product in the second heater effluent line 95. Exchanged between The dehydrogenation product is extracted from the first heat exchanger 25A via the first heat exchanger effluent line 96, and the first heat exchanger effluent containing the reactor feed is discharged to the first heat exchanger effluent. It is extracted from the first heat exchanger 25A via the liquid line 30. Further, the heat exchange of the hydrocarbon feeds extracted from the first heat exchanger 25A via the first heat exchanger effluent line 30 is performed by introducing them into the second heat exchanger 25B and flowing out of the third reaction tank 25B. It is provided by heat exchange with the product stream extracted from the third dehydrogenation reactor 65C via the liquid line 85. The dehydrogenation products are extracted from the second heat exchanger 25B via the second heat exchanger effluent line 90, and the further heat exchanged hydrocarbon feed passes through the second heat exchanger effluent line 35. Extracted from the second heat exchanger 25B. The temperature of the reaction product (ie, the heat exchange medium) in the second heat exchanger effluent line 90 is reduced to a second temperature before being introduced into the first heat exchanger 25A via the second heater effluent line 95. It can be adjusted via a passage through heater 15B.

  The diluted steam introduced via the diluted steam supply line 40 is superheated in the third heater 15C, and the superheated steam extracted from the third heater 15C via the third heater effluent line 45 is: In the fourth heater 15D, it is combined with the hydrocarbon / steam feed in the second heat exchanger effluent line 35. First stage feed steam, including hydrocarbons and steam, is extracted from fourth heater 15D via fourth heater effluent line 50.

  The splitter 55A is configured to supply the first-stage supply steam to the first dehydrogenation reaction tank supply line 65A via the first dehydrogenation reaction tank supply line 60A. It serves to split into a second or remaining portion which is introduced via 60B into a second dehydrogenation reactor 65B, which operates in parallel with the first dehydrogenation reactor 65A. The first stage feed vapor fraction introduced into each of the first and second dehydrogenation reactors may depend on their volume. For example, in retrofit applications where the first dehydrogenation reactor 65A and the second dehydrogenation reactor 65B are of different sizes, the split ratio can be adjusted accordingly. In an embodiment, about half of the first stage feed steam is introduced into the first dehydrogenation reactor 65A, and about half of the first stage feed steam is introduced into the second dehydrogenation reactor 65B. In an embodiment, the first dehydrogenation reactor 65A and the second dehydrogenation reactor 65B have approximately equal volumes.

  As described above, the first and second dehydrogenation reactors 65A and 65B are provided for dehydrogenating hydrocarbons in the first stage feed steam in the presence of steam to produce dehydrogenation products therein. A dehydrogenation catalyst suitable for catalyzing the hydrogenation. The dehydrogenation products and unreacted hydrocarbons are passed through the first reactor effluent line 70A and the second reactor effluent line 70B, respectively, to the first dehydrogenation reactor 65A and the second dehydrogenation reactor 65B. Extracted from The product streams of the first dehydrogenation reactor 65A and the second dehydrogenation reactor 65B are combined in a mixer 55B to provide a mixed first stage effluent, which may be interstage or fifth heater feed. Extracted via line 75.

  The combined first stage effluent is introduced into the interstage or fifth stage heater 15E via a stage or fifth heater supply line 75, which heats the first stage effluent to a third dehydrogenation. It serves to heat the reactor 65C to a temperature suitable for operation, ie, provides a third reactor feed (also referred to herein as a second stage reactor feed), which may be a third reactor or a second reactor. Extracted from the interstage heater 15E via the stage supply line 80. Although shown in FIG. 1 as a heater, the interstage heater 15E uses the heat exchanger shown in the embodiment of FIG. 2 via any standard reheating technique, and as discussed further below. Can be operated. In embodiments, the combined first stage effluent is heated between stages or in a fifth heater 15E via heat exchange.

As described above, the third dehydrogenation reactor 65C has a dehydration of unreacted hydrocarbons in the second stage feed in the presence of steam when introduced via the second stage feed line 80 therein. A dehydrogenation catalyst suitable for catalyzing the hydrogenation. The second stage effluent, including dehydrogenation products and any remaining unreacted hydrocarbons, is extracted from third dehydrogenation reactor 65C via third reactor effluent line 85. As described above, the second stage effluent extracted from the third dehydrogenation reactor 65C is compressed and subjected to product separation (s) to dewater from water and any reaction by-products. The digestion product can be separated. In embodiments, the effluent of the second stage may be subjected to heat exchange with the hydrocarbon / vaporized vapor feed, as described above, ie, before the compression thereof and / or the separation of the product therefrom. Condensing at least a portion of the stage effluent. For example, as previously discussed, the heat between the second stage effluent in the third reactor effluent line 85 and the hydrocarbon / steam feed in the first heat exchanger effluent line 30 is transferred to the second The second heat exchanger effluent in the second heat exchanger effluent line 90 and the hydrocarbon / steam feed in the first heater effluent line 20 can be exchanged in the heat exchanger 25B. Can be exchanged in the first heat exchanger 25A. The temperature of the second heat exchanger effluent in the second heat exchanger effluent line 90 before the second heat exchanger effluent line 95 is introduced into the first heat exchanger 25A via the second heater effluent line 95 It can be adjusted via a passage through 15B.

  Another embodiment of the dehydrogenation method according to the present disclosure will now be described with reference to FIG. In this embodiment, the diluted feed is introduced to the third heater 15C 'via the diluted steam supply line 40', and the appropriately heated steam is supplied to the third heater 15C 'via the third heater effluent line 45'. After being introduced into the heat exchanger 25C ′, the third heat exchanger 25C ′ heats the mixed first-stage effluent in the mixed first-stage effluent line 75 and then transfers it to the second stage effluent. It is configured to be introduced into the third dehydrogenation reaction tank 65C via the supply line 80. The heat-exchanged diluted steam extracted from the third heat exchanger 25C ′ via the line 41 ′ is supplied to the second heat exchanger effluent via the third heater 15C and the third heater effluent line 45. The heat exchanged hydrocarbon / steam feed in line 35 can be combined in fourth heater 15D.

  For comparison, a brief description of a conventional dehydrogenation method will now be given with reference to FIG. As described above, conventional dehydrogenation methods use a series of dehydrogenation reactors instead of parallel. Preparation of the hydrocarbon / steam feed prior to introduction into the fourth heater or "dilution steam mixing unit" 115D is accomplished by evaporating the steam feed in the steam feed inlet line 105 and in the hydrocarbon feed inlet line 110. Combining the hydrocarbon feed in a first heater 115A, wherein the hydrocarbon is vaporized to provide a first heater effluent containing the vaporized hydrocarbon feed, which is a first heater effluent. Extracted from the first heater 115A via line 120. Via a passage through the first heat exchanger 125A and the second heat exchanger 125B, the vaporized hydrocarbon feed and the third reactor effluent (ie, product stream) in the third reactor effluent line 185 Heat is exchanged between. In the first heat exchanger 125A, heat is exchanged between the vaporized hydrocarbon feed in the first heater effluent line 120 and the second heater effluent in the second heater effluent line 195. . Reaction products are extracted from the first heat exchanger 125A via the first heat exchanger effluent line 196, and the heat exchanged hydrocarbon feed is removed via the first heat exchanger effluent line 130. 1 Extracted from the heat exchanger 125A. Further heat exchange of the hydrocarbon feeds extracted from the first heat exchanger 125A via the first heat exchanger effluent line 130 is further introduced into their second heat exchanger 125B, and the third reactor It is provided by heat exchange with the product stream extracted from the third dehydrogenation reactor 165C via the effluent line 185. The reaction products are extracted from the second heat exchanger 125B via the second heat exchanger effluent line 190, and the further heat exchanged hydrocarbon feed via the second heat exchanger effluent line 135. It is extracted from the second heat exchanger 125B. The temperature of the reaction product (ie, the heat exchange medium) in the second heat exchanger effluent line 190 is increased by a second heating Adjustment can be made via a passage through vessel 115B.

The sixth heater effluent, including the diluted steam and the heat exchanged hydrocarbon / steam feed, is sent to the fourth heater 115D via the sixth heater effluent line 116 and the second heat exchanger effluent line 135, respectively. be introduced. The reactor feed is introduced into the first dehydrogenation reactor 165A via the fourth heater effluent line 150. The dehydrogenated product extracted from the first dehydrogenation reactor 165A via the first reactor effluent line 170A is combined with the steam in the fifth heater vapor effluent line 129 in the third heat exchanger 125C. Heated through heat exchange. The heat exchanged steam is extracted from the third heat exchanger 125C via the third heat exchanger vapor effluent line 126 and their temperature is increased via the sixth heater effluent line 116 to the fourth heating exchanger 125C. It is raised via a passage through a sixth heater 115F before being introduced into the vessel 115D. The elevated temperature dehydrogenation product from the first dehydrogenation reactor 165A is introduced as a feed to the second dehydrogenation reactor 165B via the third heat exchanger effluent line 127.

  The dehydrogenation product of the second dehydrogenation reactor 165B extracted therefrom via the second reactor effluent line 170B passes to the steam in the third heater effluent line 145 'in the fourth heat exchanger 125D. Heated through heat exchange with. Heat exchanged steam can be extracted from fourth heat exchanger 125D via fourth heat exchanger steam effluent line 128 and its temperature can be extracted via fifth heater steam effluent line 129. Before being introduced into the third heat exchanger 125C, it is raised through a passage through the fifth heater 115E. The dehydrogenated product at the elevated temperature from the second dehydrogenation reactor 165B is introduced as a feed to the third dehydrogenation reactor 165C via the third reactor supply line 180.

  In the conventional method of FIG. 3, the dilution steam feed in the dilution steam supply line 140 'is superheated in the third heater 115C' and appropriately heated. In a conventional manner, the superheated steam extracted from the third heater 115C 'via the third heater effluent line 145' is introduced into the fourth heat exchanger 125D, which is connected to the third reactor supply line 180D. The dehydrogenation product in the second reactor effluent line 178B is configured to be heated before it is introduced into the third dehydrogenation reactor 165C via. As described above, the temperature of the diluted steam extracted and heat exchanged from the fourth heat exchanger 125D via the fourth heat exchanger vapor effluent line 128 is equal to the temperature of the first dehydrogenation in the third heat exchanger 125C. Prior to heat exchange with the dehydrogenation product in reaction vessel 165A, it can be raised via a passage through fifth heater 115E.

Herein, a multi-stage of the present disclosure employing a first stage including two dehydrogenation reactors operated in parallel upstream of a second stage including a third dehydrogenation reactor as described above. The dehydrogenation system allows for reduced total reactor pressure, benefits of average unit pressure, increased selectivity of desired dehydrogenation products, desirable conversion, and / or low energy input per pound of dehydrogenation product In some cases. For dehydrogenation processes such as endothermic dehydrogenation of ethylbenzene to produce styrene, improved pressure conditions (ie, reduced pressure) improve selectivity. As can be seen from the examples below, it is significantly advantageous to use a first stage comprising two dehydrogenation reactors operated in parallel with a second stage comprising a third dehydrogenation reactor. The differential pressure can be reduced, which can improve the selectivity of the product. In an embodiment, the total differential pressure of the multi-stage dehydrogenation process of the present disclosure is the total differential pressure of a similar conventional method except that the first, second and third reactors are connected in series. Lower, where the total differential pressure is measured between the first reactor inlet and the third reactor outlet. In an embodiment, the overall selectivity of the multi-stage dehydrogenation process of the present disclosure is similar to that of a similar conventional method except that the first, second and third reactors are connected in series. Greater than. The total selectivity is: [moles of the desired product (eg, dehydrogenation product) produced in the first, second and third reactors] / [first reactor, second reactor and Total moles of dehydrogenated feed species (eg, hydrocarbons) converted in the third reactor]. In an embodiment, the total energy input of the multi-stage dehydrogenation process of the present disclosure is the total energy input of a similar conventional method except that the first, second, and third reactors are connected in series. Lower than.

  As can be seen when comparing the multi-stage dehydrogenation system of FIG. 1 of the present disclosure to the conventional dehydrogenation system of FIG. 3, a fifth heater 115E, a sixth heater 115F, a third heat exchanger 125C and a The four heat exchanger 125D is essentially replaced by an inter-stage heater 15E, which can serve to provide the above energy benefits of the multi-stage dehydrogenation systems and methods of the present disclosure.

The multi-stage dehydrogenation systems and methods of the present disclosure allow higher conversions to be performed in the first two reactors of the first stage (conventionally, where the first two dehydrogenation reactors are arranged in series). More reheating may be desired before being introduced into the third reactor of the second stage (as compared to the first two dehydrogenation reactors of the dehydrogenation system). In addition, the multi-stage systems and methods can be particularly well adapted to retro-operating operations used at ultra-low steam to oil (eg, about 5.5-6 STO) and low pressure.

Comparison of Conventional and Disclosed Parallel Reactor Systems Aspen Plus simulation software was used to construct the disclosed parallel reactor system shown in FIG. 1 and the conventional continuous reactor system shown in FIG. And compared. A comparison was made using a two-way reactor model at 0.37 / h ethylbenzene, 7 moles of steam to oil (STO is the mole ratio of steam to a hydrocarbon, for example ethylbenzene) and 6.5 psia outlet. Was. A pressure drop of 1.5 psia was expected in the reactor at these conditions. Table 1 provides an overview of the criteria for this comparison.

  The slightly elevated temperature of the ethylbenzene feed stream is the result of combining fresh ethylbenzene with the recycle stream, with vaporized vapor coming from the low pressure header (25 psig), diluent vapor starting at the medium pressure header (150 psig), and The garage with three cars is operated with the design of the starting conditions for the conventional method.

The following reactions were considered for both methods:
Ethylbenzene → styrene + hydrogen (1)
Ethylbenzene → benzene + ethylene (2)
Ethylbenzene + hydrogen → toluene + methane (3)

  The conversion and selectivity specifications shown in Table 2 were used.

  The experimental process system of the conventional method is specifically illustrated in FIG. 3; the experimental process system of the parallel method is specifically illustrated in FIG. 1. The heat load results for the conventional method are provided in Table 3 below, and the heat load results for the parallel method are provided in Table 4 below.

  Table 5 summarizes representative laboratory data for the standard serial format and expectations for the parallel format. The percent styrene monomer, inlet pressure, outlet pressure, percent conversion and percent selectivity in the reactor effluent are shown for three dehydrogenation reactors in standard series and parallel modes.

  As shown in Tables 3 and 4, the net energy of the conventional method is slightly lower than the parallel method. However, this may be due to the high pressure steam produced. The parallel method actually requires less energy input per pound of styrene. In addition, the method can operate at lower total pressures and higher selectivities, as demonstrated. The parallel reactor method thus demonstrates the advantages in energy input, average unit pressure, total differential pressure and total selectivity with respect to the modeled conditions.

Additional Description This disclosure may be modified and practiced differently, as specific embodiments of the above disclosure are specific only, but equivalent modes will be apparent to those skilled in the art having the benefit of the teachings herein. . Furthermore, no limitations are intended to the details of the structures and designs set forth herein, except as set forth in the following claims. It is therefore evident that the specific illustrative embodiments disclosed above may be altered or modified, and that all such variations are deemed to be within the scope and spirit of the present disclosure. Also, other embodiments arising from combining, integrating, and / or omitting features of the embodiment (s) are within the scope of the present disclosure. Also, the techniques, systems and methods described and described separately or separately in various embodiments may be combined or integrated with other systems, modules, techniques or methods without departing from the scope of the present disclosure. it can. Other items shown or considered directly coupled or communicating with one another may be electrically, mechanically or otherwise through some interface, device or intermediate component. Can also be coupled or communicated indirectly. Other examples of changes, substitutions and alternatives will be ascertained by those skilled in the art and may be made without departing from the spirit and scope of the present disclosure. Although the compositions and methods are described in broader terms than “having,” “comprising,” “containing,” or “including,” the compositions and methods include compositions. The methods and methods may be “consisting essentially of” or “consisting of” various components or steps. The use of the term "optionally" with respect to any element in a claim means that that element is required, or otherwise the element is not required, and that both options fall within the scope of the claim. Means

The number and range of the above disclosures may vary up to an amount. Whenever a numerical range with a lower and upper limit is disclosed, any number and subsumed range within that range is specifically disclosed. Specifically disclosed herein ("about a to about b", or equivalently, "approximately a to about b", or equivalently, "about (
Each range of values) (in the form of (approximately) ab) is understood to describe each number and range that encompasses the wider range of values. Also, the terms in the claims have their obvious and customary meanings unless otherwise explicitly and clearly defined by the patentee. Furthermore, as used in the claims, the article "a" or "an" is defined herein to mean one or more than one element. If there is a conflict in the usage of words and terms in this specification and in one or more patents or other documents, the definition consistent with this specification should be applied.

  Embodiments disclosed herein include:

A: Multi-stage dehydrogenation process: In a first stage, a feed stream containing hydrocarbons and steam is contacted with a dehydrogenation catalyst under dehydrogenation conditions to obtain a first stage effluent; In a second stage, contacting the heated first stage effluent with a dehydrogenation catalyst under dehydrogenation conditions to remove the second stage effluent containing the dehydrogenated product. Wherein the first stage comprises a first reactor and a second reactor arranged in parallel, and wherein the second stage comprises a first reactor and a second reactor in series. Including a third reaction vessel connected.

B: The multi-stage dehydrogenation system comprises: a feed stream comprising hydrocarbons and steam; a first reactor and a second reactor arranged in parallel, wherein the first reactor comprises a dehydrogenation catalyst. And a first reactor inlet for receiving a portion of the feed stream, wherein the second reactor includes a dehydrogenation catalyst and has a second reactor inlet for receiving the remaining portion of the feed stream; Here, the first step is to convert at least a portion of the hydrocarbon to a dehydrogenated product by contacting the hydrocarbon with the dehydrogenation catalyst under dehydrogenation conditions in the first and second reactors. And is fluidly connected to the first reactor outlet of the first reactor and receives the effluent of the first reactor and flows to the second reactor outlet of the second reactor. Stage heater connected to and receiving the effluent of the second reactor; third reaction Wherein the third reactor comprises a dehydrogenation catalyst and has a third reactor inlet in flow communication with the interstage heater, wherein the second stage comprises interstage heating. The unreacted hydrocarbon received from the reactor is converted into a dehydrogenation product by contacting the dehydrogenation catalyst and the unreacted hydrocarbon in the third reaction tank under dehydrogenation conditions, It is effective to provide a second stage effluent including effluent.

C: Multi-stage dehydrogenation process: combining steam and ethylbenzene to form a feed stream; heating the feed stream to obtain a heated feed stream; dividing the heated feed stream into a first part and a second part; Is fed to a first reactor containing a dehydrogenation catalyst, where ethylbenzene is converted to styrene; a second portion of the feed stream is fed to a second reactor containing a dehydrogenation catalyst. Where ethylbenzene is converted to styrene; recovering a first effluent containing unreacted ethylbenzene and styrene from the first reaction vessel; recovering a second effluent containing unreacted ethylbenzene and styrene from the second reaction vessel Combining the first effluent and the second effluent with the mixed effluent; heating the mixed effluent to obtain a heated mixed effluent; transferring the heated mixed effluent to a third reaction vessel containing a dehydrogenation catalyst. Feed and heat here mixed effluent Comprising and recovering a third effluent containing unreacted ethylbenzene and styrene from the third reaction vessel, at least a portion of unreacted ethylbenzene present is converted to styrene.

Each embodiment A, B and C may have one or more of the following additional elements: Element 1: wherein contacting the feed stream in the first stage: dehydrogenating the first portion of the feed stream A first reactor effluent by contacting the first reactor with the dehydration catalyst; and contacting a second portion of the feed stream with the dehydrogenation catalyst in the second reactor to produce a second reactor effluent. Including obtaining. Element 2: further comprising combining the first reactor effluent and the second reactor effluent to form a first stage effluent prior to the heating step. Element 3: further heat exchange of the feed stream with the second stage effluent, thereby condensing part of the second stage effluent; compressing the second stage effluent after the heat exchange step; and dewatering Separating the denaturation product from the effluent of the second stage. Element 4: wherein the total differential pressure of the multi-stage dehydrogenation process is lower than the total differential pressure of a similar process except that the first, second and third reactors are connected in series; Here, the total differential pressure is measured between the inlet of the first reactor and the outlet of the third reactor. Element 5: wherein the overall selectivity of the multi-stage dehydrogenation process is greater than the overall selectivity of a similar process except that the first, second and third reactors are connected in series; Here the total selectivity is: [moles of dehydrogenation products produced in the first, second and third reactors] / [in the first, second and third reactors] Total moles of hydrocarbons converted]. Element 6: where the total energy input of the multi-stage dehydrogenation process is lower than that of a similar process except that the first, second and third reactors are connected in series. Element 7: wherein the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene. Element 8: Here, each of the first reaction tank, the second reaction tank, and the third reaction tank is an adiabatic reaction tank. Element 9: Here the first stage effluent heating uses a heat exchanger. Element 10: Here the effluent of the first reactor and the effluent of the second reactor are combined to form a first stage effluent, which is fed to an interstage heater. Element 11: where the interstage heater is a heat exchanger that uses steam as the fluid to be heated. Element 12: a first heat exchanger that further exchanges first heat between the second stage effluent and the feed stream; and a second heat exchanger that exchanges second heat between the second stage effluent and the feed stream. 2 Includes heat exchanger. Element 13: a compressor further arranged downstream of the first and second heat exchangers and for compressing the effluent of the second stage; and downstream of the compressor and passing the dehydrogenated product to the second A separation system configured to separate from the stage effluent. Element 14: wherein the total differential pressure of the multi-stage dehydrogenation system is lower than the total differential pressure of a similar system except that the first, second and third reactors are connected in series; Here, the total differential pressure is measured between the inlet of the first reactor and the outlet of the third reactor. Element 15: wherein the overall selectivity of the multi-stage dehydrogenation system is greater than the overall selectivity of a similar system except that the first, second and third reactors are connected in series; Here the total selectivity is: [moles of dehydrogenation products produced in the first, second and third reactors] / [in the first, second and third reactors] Total moles of hydrocarbons converted]. Element 16: wherein the total energy input of the multi-stage dehydrogenation system is lower than that of a similar system except that the first, second and third reactors are connected in series. Element 17: wherein the hydrocarbon is ethylbenzene, and wherein the dehydrogenation product comprises styrene. Element 18: Here, each of the first, second and third reaction tanks is an adiabatic reaction tank.

  While preferred embodiments of the present invention have been shown and described, those skilled in the art may make modifications thereto without departing from the teachings of the present disclosure. The embodiments described herein are merely examples and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention.

  Many other modifications, equivalents, and alternatives will become apparent to those skilled in the art once the above disclosure is fully understood. It is intended that the following claims be interpreted as covering all such alterations, equivalents, and alternatives as applicable. Accordingly, the scope of protection is not limited to the above description, but is only limited by the following claims, which cover all equivalents of the subject matter of the claims. The individual claims are hereby included as embodiments of the present invention. That is, the claims are a further description of the invention and are an addition to the detailed description of the invention. All patents, patent applications and publications cited herein are hereby incorporated by reference.

Claims (21)

In a first stage, contacting a feed stream comprising hydrocarbons and steam with a dehydrogenation catalyst under dehydrogenation conditions to obtain a first stage effluent;
Heating the first stage effluent and, in a second stage, the heated first stage effluent with a dehydrogenation catalyst and dehydrogenation to obtain a second stage effluent containing the dehydrogenation product Contacting under oxidizing conditions,
Including
The first stage includes a first reactor and a second reactor arranged in parallel, and the second stage comprises a third reactor connected in series with the first reactor and the second reactor. ,
Multi-stage dehydrogenation method. Contacting the supply logistics in the first stage
Contacting a first portion of the feed stream with the dehydrogenation catalyst in the first reactor to obtain a first reactor effluent, and a second portion of the feed stream to obtain a second reactor effluent Contacting the portion with the dehydrogenation catalyst in a second reactor;
The method of claim 1, comprising:   3. The method of claim 2, further comprising combining the first reactor effluent and the second reactor effluent to form a first stage effluent prior to the heating step. Heat exchanging the feed stream with the second stage effluent, thereby condensing a portion of the second stage effluent;
Compressing the second stage effluent after the heat exchange step; and separating the dehydrogenated product from the second stage effluent;
The method of claim 1, further comprising:   The total differential pressure of the multi-stage dehydrogenation process is lower than the total differential pressure of a similar process except that the first, second and third reactors are connected in series, said total differential pressure being The method of claim 1, wherein the method is measured between a first reactor inlet and a third reactor outlet. The overall selectivity of the multi-stage dehydrogenation process is greater than the overall selectivity of a similar process except that the first, second and third reactors are connected in series;
The total selectivity is
[Mole of dehydrogenation product generated in first, second and third reactors] /
[Total moles of hydrocarbons converted in the first, second and third reactors]
2. The method of claim 1, wherein the method is defined as   The total energy input of the multi-stage dehydrogenation process is lower than the total energy input of a similar process except that the first, second and third reactors are connected in series. the method of.   The method of claim 1, wherein the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene.   The method according to claim 1, wherein each of the first, second and third reaction vessels is an adiabatic reaction vessel.   4. The method of claim 3, wherein the first stage effluent heating uses a heat exchanger. A feed stream containing hydrocarbons and steam;
A first stage including a first reaction vessel and a second reaction vessel arranged in parallel;
A first reaction vessel fluidly connected to the first reaction vessel outlet and receiving the effluent of the first reaction vessel and fluidly connected to the second reaction vessel outlet of the second reaction vessel; An interstage heater for receiving the effluent of the reaction vessel;
A second stage having a third reaction vessel;
Including
Wherein the first reactor comprises a dehydrogenation catalyst and has a first reactor inlet for receiving a portion of the feed stream, wherein the second reactor comprises a dehydrogenation catalyst and the feed stream comprises Having a second reactor inlet for receiving the remaining portion of the hydrocarbon and the dehydrogenation catalyst under dehydrogenation conditions in the first and second reactors with the dehydrogenation catalyst. Contacting is effective to convert at least a portion of the hydrocarbon to a dehydrogenated product;
Wherein the third reactor contains a dehydrogenation catalyst and has a third reactor inlet in flow communication with the interstage heater, and wherein a second stage is received from the interstage heater Unreacted hydrocarbons are converted to dehydrogenation products to provide a second stage effluent by contacting the dehydrogenation catalyst with unreacted hydrocarbons in a third reactor under dehydrogenation conditions. Is effective in doing
Multi-stage dehydrogenation system.   12. The apparatus of claim 11, further comprising a mixer configured to combine the effluent of the first reaction vessel and the effluent of the second reaction vessel to form a first stage effluent to be supplied to the interstage heater. System.   The system of claim 11, wherein the interstage heater is a heat exchanger using steam as a heating fluid. A first heat exchanger for exchanging first heat between the second stage effluent and the feed stream;
12. The system of claim 11, further comprising a second heat exchanger for exchanging second heat between the second stage effluent and the feed stream. A compressor configured to compress the second stage effluent and downstream of the first and second heat exchangers;
15. The separation system downstream of the compressor and configured to separate dehydrogenation products from the second stage effluent.   The total differential pressure of the multi-stage dehydrogenation system is lower than the total differential pressure of a similar system except that the first, second and third reactors are connected in series. 12. The system of claim 11, wherein is measured between a first reactor inlet and a third reactor outlet. The overall selectivity of the multi-stage dehydrogenation system is greater than the overall selectivity of a similar system except that the first, second and third reactors are connected in series. Is
[Mole of dehydrogenation product generated in first, second and third reactors] /
[Total moles of hydrocarbons converted in the first, second and third reactors]
The system according to claim 11, defined as:   13. The multi-stage dehydrogenation system of claim 11, wherein the total energy input of the multi-stage dehydrogenation system is lower than the total energy input of a similar system except that the first, second, and third reactors are connected in series. The described system.   The system of claim 11, wherein the hydrocarbon is ethylbenzene and the dehydrogenation product comprises styrene.   The system of claim 11, wherein each of the first, second, and third reactors is an adiabatic reactor. A multi-step dehydrogenation process:
Combining steam and ethylbenzene to form a feed stream;
Heating the feed stream to obtain a heated feed stream;
Dividing the heated feed stream into a first part and a second part;
Feeding a first portion of the feed stream to a first reactor containing a dehydrogenation catalyst, wherein ethylbenzene is converted to styrene;
Feeding a second portion of the feed stream to a second reactor containing a dehydrogenation catalyst, wherein ethylbenzene is converted to styrene;
Recovering a first effluent containing unreacted ethylbenzene and styrene from the first reactor;
Recovering a second effluent containing unreacted ethylbenzene and styrene from the second reactor;
Combining the first effluent and the second effluent with the mixed effluent;
Heating the mixed effluent to obtain a heated mixed effluent;
Feeding the heated mixed effluent to a third reaction vessel containing a dehydrogenation catalyst, wherein at least a portion of the unreacted ethylbenzene present in the heated mixed effluent is converted to styrene; and from the third reaction vessel Recovering a third effluent containing unreacted ethylbenzene and styrene.

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